Contact free radar level gauging is widely used for level gauging in tanks. Traditionally, radar level gauging has been used in relatively large tank installations, such as refinery tanks and tanks on cargo ships. However, applications also include smaller tanks, e.g. in process industry. When the tank is made of metal, the radar level gauge must be mounted in an opening in the tank wall, in order for the radar signals to enter the tank.
However, there also exists a large variety of commercially available storage tanks made of non-metal materials, including plastics and other materials which are transmissive to microwaves. Some tanks are portable and used for transport, while others are stationary and used mainly for storage. Fields of use include water (and rain water) storage, chemical storage, septic tanks, etc.
For such tanks, mounting in an opening in the tank wall is not necessary, and may also be technically difficult. In some cases, the tank walls are flexible, and a hole in the tank wall may not provide sufficient structural strength.
Further, many smaller tanks are manufactured in large series, and under significant cost pressure. Therefore, it is not feasible to equip the tanks with a specific interface for mounting a radar level gauge at time of production.
Based on the above, it would be desirable to provide a radar level gauge which can easily be retro-fitted to existing tanks made of a radar transmissive material, without damaging or otherwise interfering with the tank.